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FMOD(3) | Linux Programmer's Manual | FMOD(3) |

# NAME¶

fmod, fmodf, fmodl - floating-point remainder function# SYNOPSIS¶

#include <math.h>

double fmod(doublex, doubley);float fmodf(floatx, floaty);long double fmodl(long doublex, long doubley);

Link with *-lm*.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

**fmodf**(), **fmodl**():

_ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

# DESCRIPTION¶

These functions compute the floating-point remainder of dividing*x*by

*y*. The return value is

*x*-

*n**

*y*, where

*n*is the quotient of

*x*/

*y*, rounded toward zero to an integer.

# RETURN VALUE¶

On success, these functions return the value*x*-

*n**

*y*, for some integer

*n*, such that the returned value has the same sign as

*x*and a magnitude less than the magnitude of

*y*.

If *x* or *y* is a NaN, a NaN is returned.

If *x* is an infinity, a domain error occurs, and a NaN is
returned.

If *y* is zero, a domain error occurs, and a NaN is
returned.

If *x* is +0 (-0), and *y* is not zero, +0 (-0) is
returned.

# ERRORS¶

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.The following errors can occur:

- Domain error:
*x*is an infinity *errno*is set to**EDOM**(but see BUGS). An invalid floating-point exception (**FE_INVALID**) is raised.- Domain error:
*y*is zero *errno*is set to**EDOM**. An invalid floating-point exception (**FE_INVALID**) is raised.

# ATTRIBUTES¶

For an explanation of the terms used in this section, see attributes(7).Interface | Attribute | Value |

fmod (), fmodf (), fmodl () | Thread safety | MT-Safe |

# CONFORMING TO¶

C99, POSIX.1-2001, POSIX.1-2008.The variant returning *double* also conforms to SVr4, 4.3BSD,
C89.

# BUGS¶

Before version 2.10, the glibc implementation did not set*errno*to

**EDOM**when a domain error occurred for an infinite

*x*.

# SEE ALSO¶

remainder(3)# COLOPHON¶

This page is part of release 4.16 of the Linux*man-pages*project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

2017-09-15 |